**Problem**

Visually, the "extreme" outliers in the following graph are somewhat obvious:

**Question**

Given:

- Set of all temperatures*T*- Set of all years*Y*- Σ
- Sum of temperatures.*T* - Σ
- Sum of years.*Y* - N - Number of elements
(n) - Temperature of the nth element in the temperature set*T*

How do you determine if ** T**(n) is an outlier?

**Related Sites**

The math on some of these sites is a bit above my understanding:

- Multiple Outliers Detection Procedures in Linear Regression (broken link)
- M-estimator
- Measure of Surprise for Outlier Detection
- Ordinary Least Squares Linear Regression

Many thanks!